Polyketone polymers are relatively high molecular weight materials having established utility as premium thermoplastics in the production of shaped articles, such as containers for food and beverages and parts for the automotive industry, which are produced by processing the polyketone polymer according to well known methods. For some particular applications it is desirable to have properties which are somewhat different from those of the polyketone polymers. The more desirable properties of the polyketone polymers may be retained, and yet other properties improved, through the provision of a filled polymer compound. Reinforcing a polymer with a filler often provides a less expensive product, in addition to desirable properties for various applications.
Mineral-filled polyketone compounds with certain desirable properties are disclosed in U.S. Pat. No. 4,851,470 (George). The neat polyketone polymer has an unfortunate tendency to form chemical crosslinks at melt processing temperatures, as evidenced by a steady increase in melt viscosity as the polymer is processed. Mineral fillers frequently possess a variety of ionic species which are capable of intensifying melt processing problems for the polyketone polymer, such as accelerating crosslinking of the polymer, thereby limiting the melt processability of the filled polyketone compounds.
It is an objective of this invention to provide a mineral-filled polyketone polymer compound that exhibits superior melt stability during melt processing. The filled polyketone polymer compounds of the subject invention exhibit viscosity levels during processing that are unexpectedly lower than the viscosity levels typical for compounds filled with other fibrous mineral fillers, and yet exhibit mechanical properties at least equal to those of compounds filled with such other fibrous mineral fillers.